Plastic tube bodies, and method for producing them

ABSTRACT

A method for producing a tube preform using an injection molding method. An injection molding method is used to produce tube preforms which can be constructed with either one layer or a plurality of layers. The preform subsequently is heated and biaxially expanded by compressed air. A tube can be obtained which, on the one hand, has a tube shoulder with the strength provided by an industrial thread and, on the other hand, has a side wall which exhibits the softness desired for a tube.

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/716,167 filed Nov. 18, 2003, which is a divisional of U.S.patent application Ser. No. 09/171,965 filed Oct. 30, 1998, which is a371 of International Application No. PCT/EP97/02224 filed Apr. 30, 1997,all of which are hereby incorporated herein by reference in theirentirety.

TECHNICAL FIELD

The present invention relates to plastic tube bodies and to a method forproducing them. In particular, the present invention relates to a methodfor producing plastic tube bodies, in accordance with which, so-calledtube preforms are produced and then formed into the final tube shape ata later point in time.

The invention also relates to a device for the production of a tubebody, which has an input mechanism for the admission of a blow-formedthermoplastic container and an output mechanism for withdrawal of thetube body.

Finally the invention concerns a tube body, which is designed as part ofa blow-formed and biaxially oriented container made from a thermoplasticmaterial.

BACKGROUND

Various methods for producing plastic containers, for example from athermoplastic, are known in the prior art. Prior art methods haveincluded injection molding, blow molding, laminating methods, polyfoiland coextrusion methods.

An appropriate selection of material is made on the basis of the variousproperties of the component(s) with which the container is later to befilled. In addition to the control and obvious parameters such asstrength, etc., criteria for selecting the material also include theaggressivity or the volatility of the component, or a desired inertbehavior between the component and container, as is mostly necessarywith medical active substances.

Diffusion of one or more active substance components through a wall ofthe container is extremely undesirable particularly in the case ofcontainers for medical or pharmaceutical components, since the loss ofthe volatile components means that the percentage of quantitativecomposition no longer corresponds to the original data, with the resultthat a medically prescribed dosage, which is based on the originalcomposition of the substance, is no longer assured.

Furthermore, when volatile components serving as solvents diffuse out, aresultant change in consistency can lead to more rapid ageing, dryingout or poorer application properties.

Since a single material is often unable to fulfill all desiredrequirements (such as, for example, good compatibility with thecomponent(s) and impermeability for specific volatile constituentsthereof), consideration heretofore has been given to multi-layercontainers (in particular tubes) in which the various layers can beformed from different materials. For example, such multi-layercontainers have been produced by calendering methods in which thevarious materials are extruded and calendered in a roll configuration,that is to say rolled to form films or multi-layer films. The filmsproduced in this way can then be welded to shoulder pieces and/orsealing/closure pieces, which are produced, for example, by means of aninjection molding method. The shoulder pieces or sealing/closure pieces,however, do not have the properties of the multi-layer film, since theyhave been produced in a conventional way by means of injection moldingand consist of only one material layer.

A further possibility for achieving complete protection againstdiffusion is to provide high cost metal containers, which arecomplicated to produce but do provide a natural diffusion barrierbecause of the molecular density of metal. These metal containers can beprovided with an additional layer in the interior, in order to ensure aninert behavior between the fluid and container wall. The production ofmetal containers, however, is much more complicated than the fabricationitself because of the many individual steps (rolling, coating withplastic, forming the containers, folding and flanging the longitudinalseam, etc.). In addition, fabrication times and material costs aresubstantially higher.

For these reasons, consideration has been given to producing multi-layerplastic containers by using a multi-layer injection molding method. Sucha method is disclosed, for example, in EP 0 537 346 A. The first step inthis method is to inject a so-called enveloping layer into the injectionmold, followed by, or simultaneously with a so-called core layer thathas previously been formed by using a forming agent. The result is acontainer with a two-layer wall with the layers formed by differentmaterials.

A further problem to be considered in producing plastic containers isthe transportation size of the containers. More particularly, theplastic containers usually are not produced at the location where theyare later filled with the component, but instead by a supplier at adifferent location. Since plastic containers for some applications maybe of considerable size, yet light in weight, a transportation problemarises to the extent that in relation to the weight of the goods to betransported, the freight charges are also calculated in part on thebasis of the volume of the goods. Consequently, with large-volume(empty) containers, transportation is relatively costly since, forexample, a truck is essentially transporting “air”.

For this reason, it has already been proposed to supply plasticcontainers to the consumer not in their final form, but in the form ofso-called preforms. EP 0 374 247 A1 and EP 0 325 440 A2 are examples inthis regard. Injection molding methods for producing multi-layercontainer preforms are described in these documents.

An example of plastic containers are tubes that are presently widelyused, for example, in the field of medicine, in cosmetics, for dentalcare agents and in nutrition. The tubes comprise tube body and a tubeclosure, such as a cap, usually produced by injection molding. The tubebody should desirably have a firm shoulder region provided with a screwthread having sufficient strength to seal the tube reliably with thetube closure. It is to be kept in mind here that, by contrast withplastic bottles, tubes typically use industrial threads that are notpositively disengaged from a mold but instead are turned out of themold. Moreover, the tube body should have a side wall that gives theuser the required “feeling of a tube”, specifically a sufficiently softconsistency which permits the mostly highly viscous component to becompletely dispensed by squeezing the tube.

To date, tube bodies have been produced in two different ways which areknown in the prior art as the “KMK” method and the “AISA” method. Thesetwo methods are described below with reference to FIGS. 13 and 14.

The “KMK” method is shown diagrammatically in FIG. 13. As may begathered from the representation, a cylindrical tube 600, whichcorresponds to the later formed tube side wall, is introduced into amold cavity 500. The tube 600 may be formed from a (multi-layer) filmwhich has been produced using the calendering method explained above,and thus has a welded seam 610. After the tube 600 has been moved intothe cavity 550 of the mold 500, plastic 510, for forming the tubeshoulder, is introduced into the mold cavity 550 as a “sausage” in theshape of a circle. In a subsequent step, the tube shoulder is thenformed by a punch 520 which is lowered into the mold cavity 550 of themold 500.

In accordance with the “AISA” method shown diagrammatically in FIG. 14,a tube side wall 600 (which can be produced as previously described inconnection with the KMK method) is introduced into an alreadyprefabricated tube shoulder 550′.This tube shoulder 550′ can have beenproduced previously by injection molding. The elements of tube shoulder550′ and tube side wall 600 thus assembled are then welded, for exampleby means of high frequency or hot air.

Both of the previously mentioned methods ensure that the tube bodyproduced meets the various requirements made of the tube shoulder andtube side wall. Disadvantages of these production methods include arelatively complicated and cost-intensive manner to produce the tubes,and the tubes having to be moved in their final size to a customer'slocation where the tubes are filled, whereby the full size tubes occupya substantial volume for transportation and storage.

Such tube bodies can be referred to, for example, as tubes according togeneral linguistic usage, with a neck section provided with a thread ora resilient cam and/or a relief, on which a turning catch is provided.The tube has a shoulder section between the neck or closure section anda main part of the tube.

Usual production procedures for the production of such tubes are, forexample, the production of tube section preforms from a foil material,which is welded afterwards with a injection molded closure sectionprovided with a shoulder section. Likewise, so-called deep-drawingprocedures exist, with which the tube bodies from injection moldedpreforms are produced.

In WO 97/40972, the production of a tube body is described, with which afirst container body is blow formed, and afterwards an end region of thecontainer is cut open.

For the blow formed production of containers from preforms, differentprocedures and devices are well known for spraying and pouring beforeblow forming.

The preform is blow formed into a container after a thermalconditioning, using a blow tube. Stretch pins are positioned bypneumatic cylinders or a circulating control.

During blow molding of a container, preforms made of a thermoplasticmaterial, such as PET (polyethylene terephthalate), are positioned atrespective work stations in a blow molding machine. A blow moldingmachine typically includes a heating mechanism as well as a blowingmechanism. The preform is heated to and kept at a moderate temperaturebefore biaxially expanding the preform to form a container. Theexpansion takes place by compressed air, which is introduced into thepreform. The process engineering operational sequence with an expansionof the preform is explained in DE-OS 43 40 291.

An exemplary container blow molding station is described in the DE-OS 4212 583. Possibilities for keeping the preform at a moderate temperatureare explained in the DE-OS 23 52 926.

Within the blow molding device, the preform as well as the blowncontainers can be transported with the help of different handlingmechanisms, such as those wherein the preform is retained by use oftransportation elements. In addition, the preform can be handled withother carrying mechanisms. The use of grippers for the handling ofpreforms and the use of expanding mandrels are also known.

The handling of the preform can take place using a so-called two-stageprocedure, with which the preform is manufactured first in an injectionmolding procedure, stored temporarily afterwards and later heated andblow molded to form a container. Alternatively, the preform may be keptat a moderate temperature immediately after injection molding thereofand a sufficient solidification, and then thereafter blown to form acontainer.

Various types of blow molding stations are well-known. The blow moldingstations may be located on rotary wheels, and book-like hinged preformcarriers may be used. In addition, preform carriers may be differentlyarranged relative to one another.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for producingand/or filling fillable plastic tube bodies and/or containers in asimple, cost-effective and/or space-saving manner.

In a general sense, the invention provides a method for producing a tubepreform using an injection molding method.

The inventor of the present invention has found that in the case ofproducing tube preforms using an injection molding method and ofsubsequent extension, in particular by heating the preform and biaxialexpansion, a tube can be obtained whose tube shoulder, on the one hand,has the strength required for an industrial thread, and whose sidesurface, on the other hand, exhibits the softness desired for a tube.

In accordance with a first preferred embodiment, a first step isadvantageously to produce a tube body preform which has a shoulderregion, open towards the interior of the tube body preform, and a closedend region. The tube body preform produced in such a way can then betransported to the filler, where it is first heated in a first methodstep, and then brought into its final shape and size with the aid ofbiaxial expansion. Finally, in a subsequent method step, the closed endregion of the tube body is cut open in order to permit the plastic tubeto be filled with the desired component. The use of biaxial expansion(by contrast with the axial expansion in the case of cold stretching,for example) renders it possible to use transparent tube materials thatexhibit a glass-like transparency even in the expanded state.

The biaxial expansion of the tube body preform may be advantageouslyperformed by means of compressed air in a blowing method, only the tubeside wall being expanded while the tube shoulder stays in its originalshape. The biaxial expansion thus effected renders it possible toproduce a tube with a side wall that is characterized to a particularextent by the desired “feeling of a tube”, that is to say the softnessof a squeezable tube. Furthermore, the tube side wall produced in such away has particular strength.

The tube body preform may be advantageously produced using an injectionmolding method. This permits the tube body preform to be produced in anextremely cost-effective way and with a high quality.

If the biaxial expansion of the tube preform is performed withcompressed air, prior heating of the preform can advantageously beperformed using infrared light.

If a plastic tube produced in accordance with the invention is, forexample, to be printed with a product designation, this may take placeafter the expansion of the preform, and advantageously after the closedend region of the tube body has been cut open.

The plastic body preform has a closed end region that enables blowmolding of the tube body, as by biaxial expansion.

According to another aspect of the invention, the tube preform may be ofa multi-layer configuration. For this purpose use may be made of aninjection molding line having at least two feeding containers, withdifferent materials being introduced into the feeding containers. Afterthe materials have been plasticized, they may be forced through anannular nozzle with concentrically arranged annular nozzle gaps, and thedelivery rates of the materials may be substantially the same in termsof direction and magnitude, with the result that the homogeneity of thefirst and second materials is maintained after they leave the nozzle.The materials thus plasticized are then injected into a mold cavity ofan injection mold, it being the case here, as well, that the homogeneityof the material layers may be maintained in the mold cavity. A tubepreform produced in this way is then formed into the final tube in asubsequent method step, use advantageously being made for this purposeof the herein described blow molding method. One advantage of thesemultilayer tube preforms is the possibility of producing tubes withalready integrated closure and shoulder regions, which are distinguishedby being completely multilayered.

The invention also provides a method of the kind specified wherein highproduction rates are supported with good product quality.

More particularly, the invention provides a method of forming acontainer comprising the steps of:

-   -   a) injection molding a preform from a thermoplastic material,    -   b) placing the preform into a blow mold,    -   c) biaxially expanding the preform to form a container through        stretching and supplying of a pressurized blowing gas,    -   d) removing the containers from the blow mold,    -   e) cutting off the containers end region to form an open end,    -   f) pressing together the open end, and    -   g) welding the open end.

Air may be used as the blowing gas.

According to another aspect of the invention, there is provided a devicefor carrying out one or more of the above method steps. Such a devicemay have a container input mechanism, a container output mechanism, anda cutting mechanism located between the input and output mechanisms forcutting off an end region of the container opposite the closure sectionof the container.

According to a further aspect of the invention, there is provided a tubebody of the kind specified that can be industrially produced. A finalsection of the tube body, which is opposite a closure section, is weldedto close an open end formed by a separation of a end region from thebalance of the container from which the tube is formed.

More particularly, an end region of the container is completelyseparated from the balance of the container. The end region that issevered preferably extends into the typically cylindrical side wallregion of the container that extends from the closed end of thecontainer to the closure region. The exact location of the cutting planecan determined as desired for a particular application. The separationof the end section need not necessarily be along a plane or along aplane perpendicular to the center axis of the container, but instead mayextend at an incline to the center line. Preferably the open end isbounded by a smooth edge, but this may be varied with the nature of theedge being determined in part by the cutting tool. In addition, theoutline of the edge can be adapted to different production requirementsor to a particular product design. For example, the edge may beconfigured to provide a wave-like appearance suggesting a coolingeffect.

High production rates are supported in particular by the fact that theproduction of the container can be accomplished in a two-stageprocedure.

In order to provide a desired strength, a stretch pin or pins may beused during blow molding of the container.

The container may be made from a preform with a single-layer structureor from a preform with a multi-layer structure. With a multi-layerstructure, a layer can be prepared as a barrier layer inhibitingpermeation of gases through the side wall of the container that mightotherwise occur for the given component to be contained within thefinished tube. An innermost layer may also be selected to facilitatefilling and/or dispensing of a product, as by minimizing adherence ofthe product to the side wall of the container/tube.

A production procedure may be accomplished in such a manner that aflask-shaped container is manufactured.

In accordance with a particular application, the tube body ismanufactured as a tube, and particularly a tube formed from a bottle K.

In accordance with another embodiment, welding the open end isaccomplished before filling the tube container.

In accordance with another embodiment, welding of the open end isaccomplished after the tube/container is filled.

A compact production plant may be made available by the fact that theinput mechanism of the cutting mechanism is coupled with a blow moldingapparatus.

An integrated plant concept may also involve the output of the assemblyused to cut the ends of the containers may be coupled to the input of afilling assembly.

Additionally, the cutting mechanism may be coupled with weldingequipment.

The tubes produced from the tube preforms are suitable for a variety ofuses such as, for example, tubes for cosmetic, medical, pharmaceuticaland hazardous media or foodstuffs, etc.; and semi-rigid tubes forcleaning agents, chemicals, biological materials or consumer articles,etc.

Tube preforms according to the invention may provide one or more of anumber of advantages. One advantage resides in very low productioncosts, since the steps, otherwise required, of inserting shoulder piecesand welding the parts to one another, for example, are no longerrequired. Furthermore, in the case of multi-layer tube preforms, thespecific dosing of the individual thermoplastic materials renders itpossible for cost-intensive constituents to be optimally set, somethingwhich can have a substantial effect on the production costs.

The foregoing may be explained using an example. Consideration is givento a previously known tube whose wall consists of three material layers,the middle layer being an expensive diffusion-inhibiting material. Thislayer makes up approximately 80-90% of the tube volume; only 10-20% ofthe tube volume is due to the cost-effective inner and outer layers. If,for example, PE is used as a cost-effective outer or inner material(approximately 1.60 DM/kg) and EVOH as the expensive middle material(approximately 12 DM/kg), this would mean material costs ofapproximately 10.96 DM/kg for an average tube. A reduction in cost toapproximately 2.64 DM/kg can be achieved with the method according tothe invention by optimizing the use of materials.

A further advantage resides in the fast injection technique forproducing preforms, since previous containers have had to be produced byextrusion, a technique which requires equipment which is morecost-intensive and has longer production cycles.

A further advantage consists in the possibility of being able to operatea plurality of injection molds, specifically up to 144, in parallel.

Other advantageous developments of the invention will become apparentfrom the following description of exemplary embodiments of the presentinvention that are explained below in detail with reference to thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the annexed drawings:

FIG. 1 is a perspective representation of a blowing station for theproduction of containers from preforms;

FIG. 2 is a profile of a blow mold, in which a preform is expanded andstrained;

FIG. 3 is a schematic illustration of a device for blow moldingcontainers;

FIG. 4 is a modified heating area with increased heating capacity;

FIG. 5 is a side view of a container with separated end region;

FIG. 6 is a schematic representation of a production plant for theproduction and filling of tube bodies;

FIG. 7 is a perspective view of a tube body prepared as a bottle;

FIG. 8 is schematic illustration of an injection molding apparatus forproducing the preforms according to the invention;

FIG. 9 is a cross-sectional view of a blown multilayer bottle, togetherwith the detail K;

FIG. 10 is an enlargement of the layered structure of detail K of FIG.9;

FIG. 11 are schematic illustrations showing a number of possible layerdesigns for a multilayer preform according to the present invention;

FIG. 12 is a perspective view, partly broken away in section, of aninjection-molding apparatus for use in multilayer injection moldingmethod; and

FIGS. 13 and 14 are schematic illustrations of methods for producingtube preforms according to the prior art.

DETAILED DESCRIPTION

FIGS. 1 and 2 disclose exemplary blow molding equipment formanufacturing intermediate product containers. The principal componentsof the equipment for the shaping of preforms 1 into containers 2 areshown.

The device for the molding of the container 2 essentially comprises ablow molding station 3, where a blow mold 4 is provided and into which apreform 1 is placed. The preform 1 can be formed, for example, in wholeor in part from polyethylene terephthalate, polypropylene, mixturesthereof, or other suitable materials.

To allow for insertion of the preform 1 into the blow mold 4 and forremoval of the finished container 2, the blow mold 4 if formed byhalf-molds 5, 6 and a floor part 7, which are positionable by anactuating device 8. The preform 1 can be delivered to the blow moldingstation 3 by a transport element 9, which together with the preform 1moves through a plurality of treatment stations within the device. Inaddition, it is possible to insert the preform 1, for example, by theuse of a gripper or other handling means directly into the blow mold 4.

A blow rod 10 is arranged underneath the transport element 9, for use insupplying compressed air to the interior of the preform 1, and at thesame time insulating the transport element 9. In a modifiedconstruction, compressed air supply lines may be used.

Stretching of the preform 1 can be completed with the help of a stretchpin 11, which is positioned by a cylinder 12. In another embodiment, amechanical positioning of the stretch pin 11 may be accomplished by useof guide rollers riding on a curvilinear surface of cam segments. Theuse of curved cam segments is appropriate, in particular, if a pluralityof blowing stations 3 are arranged on a rotary blowing wheel.

In the embodiment shown in FIG. 1, the stretch pin system has a tandemarrangement made available by two cylinders 12. The stretch pin 11 maybe driven first by a primary cylinder 13 before beginning the actualstretching of the body 14 of the preform 1. During the actual stretchingprocedure, the primary cylinder 13 is positioned together with thestretch pin by a carriage 15 that is moved by a secondary cylinder 16over a reciprocating control. In particular, using the secondarycylinder 16 in such a manner, a cam controlled by a guide roller 17,which protects the procedure of driving the stretch pin along a coursealong slides is given. The guide roller 17 is driven along the path bythe secondary cylinder 16. The carriage 15 slides along two drivingelements 18.

After getting within the range of the mold carriers 19, 20 the arrangedhalf-molds 5, 6 are secured by a mold latch 40 near the mold carriers19, 20, which takes place with the help of a bolting device.

To use preforms with closure sections 21 different than the preform 1 inaccordance with FIG. 2, the use of separate neck clamps 22 within theblow mold 4 is contemplated.

Additionally, FIG. 2 shows a container 2, a developing blown container23, and also a preform 1.

FIG. 3 shows the fundamental structure of a blowing machine, which isprovided with a heating area 24 as well as a rotary blowing wheel 25.The preform enters from the preform input 26, then the preform 1 istransported by delivery wheels 27, 28, 29 into the heating area 24.Along the heating area 24 a heating emitter 30 as well as a blower 31are arranged, in order to keep the preform 1 at a moderate temperature.While keeping it at a moderate temperature, the preform 1 is transferredto the rotary blowing wheel 25, in which the blow molding stations 3 arearranged. The finished blown containers 2 are transported by additionaldelivery wheels to a distribution area 32.

In order to be able to transform a preform 1 into a container 2 in sucha manner where the container 2 exhibits material properties ensuring along life of substances within the container 2, in particular beverages,the heating and orientation of the preform 1 is maintained. Beyond that,favorable effects can be obtained by adherence to dimensionspecifications. The use of the tubes and/or bottles according to theinvention makes possible, for example, the packing of medical, cosmetic,pharmaceutical and chemical contents, in particular, adhesive materials.

In addition to thermoplastic material, different plastics can be used.For example PET, PEN, Pa or PP are operational.

The present invention refers to, in particular, the new use of tubesand/or bottles for the packing or handling of the below mentionedproducts.

The expansion of the preform 1 according to the procedure takes placevia admission of compressed air. A gas (e.g. compressed air) is suppliedduring an initial blowing phase at a low pressure, and is supplied at ahigher pressure level during a main blowing phase. During the initialblowing phase, typically, compressed air with a pressure in the intervalfrom 10 bar to 25 bar is used and during the main blowing phasecompressed air with a pressure in the interval from 25 bar to 40 bar issupplied.

In the embodiment illustrated in FIG. 3, the heating area 24 is composedof a plurality of chain-like transport elements 33, which are guided bya chain trained over wheels 34. In particular, the chain-likearrangement is an essentially rectangular shape or outline. When theshown embodiment is within the range of where the delivery wheel 29 andan input wheel 35 are located, the heating area 24 should be expanded tothe area within the range of where the largely dimensioned returningwheel 34 and the two comparatively smaller dimensioned returning wheels36 are used. In addition, in principle, arbitrary other guidances areconceivable.

The illustrated arrangement proves relative to making as close anarrangement of the delivery wheel 29 and the input wheel 35 as possibleto each other as particularly appropriate, since in the range of theappropriate expansion of the heating area 24 three returning wheels 34,36 are encompassed. In each case the smaller returning wheels 36 arewithin a linear range of the transition of the heating area 24 and thelarger returning wheel 34 is in an area opposite the delivery wheel 29and to the input wheel 35. Alternatively, in the use of chain-liketransport elements 33, it is also possible to use a rotary heatingwheel.

After completion of the blowing operation, the containers 2 are led outby a removal wheel 37 from the blowing stations 3 to the delivery wheel28, then to the distribution wheel 38 and then to the distribution area32.

In FIG. 4 a modified heating area 24 is shown, which can be kept at amoderate temperature by the larger number of heating emitters 30, and alarger quantity of preforms 1 can be processed for the same amount oftime. The blowers 31 introduced here blow air into cooling air channels39, which are opposite the heating emitters 30, and in each casedischarge the cooling air through openings in the delivery system. Adirection of flow for the cooling air is realized by releasing it in thedirection transverse to a transport direction of the preform 1. Thecooling air channels 39 can be made available within the area of theheating emitters 30, opposite the surface reflectors for the heatingradiation. It is likewise possible that the delivered cooling air couldcool the heating emitters 30.

The production steps were explained in detail for the production of thecontainer 2. FIG. 5 provides an explanation of the production of thefurther production steps. For the production of a tube container 41 anend region 42 is separated from the container 2. This can take placemechanically or under employment of other suitable separation processes.The end region 42 is removed from the tube container 41 and can form afurther closure section, where, for example, a recycling material can beused.

In FIG. 6 a production plant is shown, with which all production stepsare locally accomplished. Granulate-like raw material 43 is driven to aninjection molding mechanism 44 and transformed to the preforms 1. Thepreform 1 is driven to a blower 45 and transformed into the container 2.The containers 2 are supplied afterwards to a cutting mechanism 46,which separates the end regions 42 of the remainder of the container 2and thereby makes the tube containers 41 available. The tube containers41 are supplied in a further production step of a filling mechanism 47,which brings a filling material into the tube container 41. With aprocedure as such, the one closure section 21 of the tube container 41is first sealed. This can take place for example via screwing on orlifting up a cover and/or applying a closure sealing. The fillingprocedure is thus accomplished by the open end opposite the closuresection 21 in the tube container 41, which was produced before bycutting the end region 42 off.

In a locking production step of the filled tube container 41, weldingequipment 48 is supplied, which welds the still open closure section 21for an opposite range of the tube container 41 in the range of an openend 49.

Deviating from the production concept in FIG. 6, different variants canbe realized. In particular it is not necessary to operate allillustrated components in common. For example it is possible to operatethe injection molding mechanism 44 locally, separately from the blower45 and to temporarily store and/or transport the manufactured preform 1.Likewise it is possible to combine the injection molding mechanism 44and the blower 45 into a common single-step plant.

The presented order of filling the tube body 41 in a first step and ofwelding the open end in a second step can alternatively be accomplishedby, first welding the open end and then filling the tube containerthrough the closure section 21. The actually selected sequence of theproduction steps only takes place as a function of the defaults of arespective user and on the characteristics of the product which can befilled up.

In accordance with FIG. 6, the cutting mechanism 46 is at the input sideprovided with an input mechanism 50 and at the output with outputequipment 51. Between the input mechanism 50 and the output equipment 51a separator 52 is provided.

In accordance with a special process step, it should also be rememberedto work on the open end again after the execution of the weldingprocedure in order to reach an optimally arranged edge outline. Inparticular it should be remembered to be completed after the executionof the welding procedure by cutting of the edge along the welding seam.Thereby a flat edge is made available, which avoids sharp and/or roughupper edges. The cutting process can be accomplished for examplemechanically or using another method in the described cutting orseparation processes.

As a function of respective application and production conditions, thecutting process can take place in the area of the welding edge both atan empty tube body and after the execution of a filling procedure.

FIG. 7 shows, an example of the invention, in accordance with theprocedure, a manufactured bottle. Such bottles can be filled withdifferent products, for example with silicone materials. Other usesconcern chemical products such as fats, adhesives or foam-endsubstances. During the production of such a bottle, in contrast to thedescribed production sequence, there is no welding of the tubecontainers 41 in the range of the open end 49, but the closure section21 opposite the open end of the tube container 41 by a floor part 53 iswelded. The floor part 53 is arranged here opposite the inside of thetube container 41.

After filling the bottle through the open area provided by the floorpart 53 into a suitable device, for example a bottle pistol, the floorpart 53 can be moved in the direction of the closure section 21 byapplying a force on the floor part 53, and the product filled up therebyfrom the one closure section 21, which was closed before.

In accordance with the invention, during the production of a tubecontainer can be varied by shaping the wall ranges within a wider range.To make certain that the production of a bottle with tube containers 41along the floor part 53 is at least in the range of the tube containers41, it is arranged in an essentially cylindrical shaping processes. Thecylindrical shaping currently supported is easily shifted to the floorpart 53 and avoids leakages. A sufficient tightness can be supportedbeyond that by a suitable sealing rim or different shapes at the edge ofthe floor part 53.

As already explained above, from the widest point of view the inventionconsists of the idea of firstly using an injection molding method toproduce blown tube preforms instead of finished tubes. These preforms(or blanks) have the advantage that they can be produced with largesavings in material. The reason for this resides in the wall thicknessof the tube side wall, which is important for the desired softness ofthe later side wall. To be precise, because of the material-specificviscosity of plasticized polymers, it is impossible to injectthermoplastics with less than a specific minimum wall thickness,particularly if multilayer tubes need to be injected.

This problem is solved by the injection molding of inventive preforms,because the side wall of the preform is not injected with the finaldimensions of the later tube (only the tube shoulder is injected withthe final dimensions). The final dimensions of the preformed side wallare reached only by later secondary finishing methods, which are usuallycarried out only by the consumer of the tube preforms.

The aim below is to describe, with reference to FIG. 8, the principle ofthe design of an injection molding apparatus which can be used toproduce the inventive tube preforms. It is important here to note thatthe injection molding apparatus shown in FIG. 8 is suitable both forproducing simple (that is to say single-layer) preforms and forproducing the particularly preferred multilayer preforms as will beexplained below.

FIG. 8 represents a multiplicity of feeding devices 60 a, 60 b, . . . 60i, . . . 60 n, which in each case represent integrated devices forconveying, plasticizing and metering thermoplastic materials. The number60 i of the feeding devices is determined by the number of plastics tobe used, and by the number of the material layers to be produced. Thus,for example, the production of a single-layer tube requires the use ofonly one feeding device 60 i, which can be filled with a desiredmaterial. A two-layer tube (in which the outer layer consists, forexample, of PP, and the inner layer of PA) requires the use of twofeeding devices 60 i in which, respectively, PP or PA are conveyed,plasticized and metered. However, in the case of a three-layer tube,which is to have a further layer made from PP, for example, as innerlayer, there is no need to use a further feeding device 60 i, it ispossible instead to undertake an appropriate subdivision (not shown) ofthe mass flows inside the lines 100, 200, 300, . . . to the nozzle 70,for example by means of a suitable valve arrangement.

Inside the feeding devices 601, the material is made available by beingintroduced into the accumulators 63 a, 63 b, . . . , 63 i, . . . , 63 n,and is conveyed by screws 22 into regions 21, in which it is plasticineby the influence of heat.

The plasticized material is fed into a line network 100, 200, 300, inwhich it continues to be held plasticized by control mechanisms (notshown), with the result that when they reach the injection nozzle 10 thethermoplastic materials are in a state which is optimum for injectionmolding methods.

The plasticized materials are introduced into the mutually “separatedannular gaps 120, 220, 320 (compare FIG. 12) of the nozzle 70 throughthe inlets which are arranged in the nozzle and communicate directlywith the respective lines 100, 200, 300.

The inlet rate and the conveying pressure depend on the respectivenozzle geometries, it being necessary inside the nozzle to take accountof the shear forces and compressive forces which arise, in such a waythat the delivery rate of the individual materials and layers areessentially the same in terms of direction and latitude.

It is possible, through ensuring this feature, for the homogeneity ofthe various layers to be maintained after they leave the annular gaps,since the layers do not mix with one another, that is to say the spatialunit of the individual layer components (for example PA, PET, EVOH,etc.) is essentially maintained in a layered fashion, with the resultthat continuous component layers are to be found.

The material, which is still plasticized, is injected into an injectionmold 80 (compare FIG. 8 ), it being possible to construct the latter indifferent ways corresponding to the preform to be produced. In the mold80 shown in FIG. 8, it is to be borne in mind that it permits theproduction of tube preforms 80 which have an open end region 95 (compareFIG. 10, a tube preform 90 being shown here which has a closed endregion 95). The production of a tube preform 90 with an open end regionis advantageous to the extent that the later filling of the finishedtube is performed via the end region 95 of the tube 90, the result beingan already appropriately open tube. A disadvantage of a tube preform 90with an open end region 95 consists, however, in that monoaxialexpansion methods such as cold-stretching methods are, in particular,the ones which come into consideration for the secondary finishing stepto produce the final tube dimensions. These methods have thedisadvantage that they place extreme loads on the plastic, and lead toincreased brittleness of the later tube. Moreover, they have the effectthat the side wall becomes milky, and thus unattractive, at least fortubes to be used in cosmetics. Consequently, according to the invention,it is regarded as particularly advantageous to produce tube preforms 90with a closed end region 95 (as shown in FIG. 10), which can be broughtto their final size with the aid of biaxial expansion methods (comparefurther below in this regard).

The solidification phase, which can be supported by a cooling system inthe injection mold 80, begins as soon as the mold 80 is fed theplasticine material.

Since, as a rule, the mold 80 consists of a plurality of parts, openingthe mold releases the workpiece such that it can easily be ejected.

Injection molding technology can be used to connect a multiplicity (upto approximately 40 of injection molds 80 to the conveying devices 60 i,with the result that a high rate of production can be achieved. Thenumber of tube layers to be produced depends on the individual materialcharacteristics, on their various physical properties, and on thespecifications of the tubes respectively to be produced.

FIG. 10 shows in cross-section an inventive tube preform which isconstructed as a preferred embodiment in three layers. The preform 90shown has a shoulder region 93 (consisting of the actual tube shoulder91 and a closure region 92, as well as a side wall region 96 which isprovided with a closed end part 95. Instead of the thread design shownin the closure region 92, it is also possible to provide anotherpossible closure, for example a hooded cap or a hinged lid.

Common to the shoulder regions and side wall regions 93,96 in themultilayer tube preform shown is the enlarged region shown in the detailK which reproduces the cross-section of the container wall. The detail Kshown in FIG. 10 shows a 3-layer wall, but equally possible are doublewalls or multilayer walls of which a few exemplary combinations areshown in FIG. 11. What is decisive is that the number of layers isidentical in all regions, the container thus being formed in one piecein one production operation.

Different variations of layers are shown in FIG. 11, the differentshadings corresponding to different materials. Only a few possiblecombinations are presented as material combinations.

The thermoplastic materials which can preferably be used for the methodare generally polymers such as polyethylene (PE) or polyethyleneterephthalates (PET), polyethylene glycol terephthalates orpolypropylene (PP). Polyamide (PA) or ethylenevinyl alcohol (EVOH) canbe used for possible further layers situated between the inner or outeredge layers. However, it is also possible to use any other plasticswhich are melt processable.

FIG. 12 is a diagrammatic perspective representation of an injectionmolding nozzle 70 according to the invention, by means of whichthree-layered tube preforms can be produced. The injection moldingnozzle 70 has three annular gaps 120, 220, 320 which in each case injecta layer of the tube preform into the mold 30 (compare FIG. 8). Theannular gaps 120, 220 and 320 are arranged concentrically and radiallyspaced from one another.

In addition, the annular gaps can have an axial spacing (not shown).

The annular gaps are connected by bores to a line system 100, 200 and300 which is connected to the conveying devices 60 i (compare FIG. 8).Of course, the number of feed lines, and thus of annular gaps is notlimited to the number shown, but depends, as already described, on thenumber of layers desired. In the diagrammatic representation, the nozzle70 is to be seen in one piece, but unipartite production can be verycomplicated, with the result that a multipartite design, for examplethrough screwed or welded joints, can be more favorable for production.

After an inventive preform 90 (which can be either of single-layer ormultilayer design and can have an open or closed end part 95 has beenproduced, the preform is advantageously moved to the filler, where theside wall region 96 is brought to its final dimensions using a secondaryfinishing method.

There is a particularly advantageous secondary finishing method forpreforms with a closed end region 95 which can consist of anythermoplastic and, in particular, of PET, PP and Grivery (amorphouspolyamide). In this method, the preform is heated in the region of theside wall, preferably using infrared radiation, until the side wallbecomes soft. The preform is then introduced into a mold which withregard to the tube shoulder region, surrounds the preform in aself-closed fashion, and with regard to the lateral region prescribesthe final shape of the later tube. Then, preferably with the aid of anair mandrel, compressed air is blown into the heated preform until theside wall has reached its final size and shape. Of course, in this casethe wall thickness of the individual layers is reduced. It is possibleusing this method for the wall thickness of the layers, which consist ofcost-intensive materials, to be greatly reduced (to below 50 μm), withthe result that a substantial cost component can be saved (up to 50% bycomparison with conventional tubes). Furthermore, the reduction in wallthickness renders the tube containers softer and thus easier to handle.

Finally, in the last operation, the closed (as before) end region of thenow finished tube is cut open perpendicular to the tube longitudinalaxis (compare the line of section S in FIG. 9) in order to provide thefilling opening.

An alternative secondary finishing method in accordance with a furtherpreferred embodiment of the present invention is a monoaxial expansionmethod, which is suitable for tube preforms with an open end region 95(compare FIG. 10). An example of such a method is a cold-forming methodin which the tube preform 90 is stretched cold in its longitudinaldirection. In this case, the side wall of the preform 90 is stretched toabout 3.5 times or more of its length.

Since no molding methods and cold stretching methods are sufficientlyknown to the average person skilled in the art, no attempt will be madehere to consider them in detail.

Finally, it is pointed out that the examples shown above are merelyexplanatory and are not to be construed in a way which limits the extentof protection. The latter is to be defined only by the attached claims.

Appended hereto is an Appendix from which the foregoing description wasderived, which Appendix is hereby incorporated herein by reference inits entirety. The Appendix refers to the same drawings annexed to thepresent application.

1. A method for producing fillable plastic tube bodies, comprising thesteps of: a. injection molding a tube body preform which has a shoulderregion that open towards the interior of the tube body preform, and aclosed end region; b. heating the tube body preform; c. biaxiallyexpanding the tube body preform in order to form a tube body; and d.cutting open a closed end region of the tube body to form a cut-open endof the tube body.
 2. The method according to claim 1, wherein step cincludes blow molding the tube body from the preform.
 3. The methodaccording to claim 1, wherein step b includes heating the tube bodypreform by means of infrared radiation or hot air.
 4. The methodaccording to claim 1, comprising the step of printing the biaxiallyexpanded tube body with a desired tube inscription.
 5. The methodaccording to claim 1, comprising the steps of: e. filling the biaxiallyexpanded tube body with desired contents via the cut-open end of thetube body; and f. closing the cut-open end of the tube body by means ofwelding.
 6. The method according to claim 1, wherein step a comprises:g. filling at least two feeding containers, respectively, with first andsecond thermoplastic materials; h. plasticizing the first and secondthermoplastic materials in the respective feeding containers; I.injecting the first and second thermoplastic materials through anannular nozzle having at least two concentrically arranged annularnozzle gaps at essentially the same delivery rate in terms of directionand magnitude for the first and second materials, with the result thatthe homogeneity of the first and second materials is maintained afterthey leave the annular gaps; and j. directing the plasticized materialsinto a mold cavity of an injection mold as they leave the annular nozzlewith the homogeneity the materials being maintained in the mold cavity,the mold cavity defining the shape of the tube body preform.
 7. Themethod according to claim 6, wherein thermoplastic material injectedthrough an outer one of the annular gaps can be welded.
 8. The methodaccording to claim 6, wherein the thermoplastic material which isinjected through an inner one of the annular gaps is selected to becompatible with the substance to be contained in the tube body.
 9. Themethod according to claim 6, where at least one further material layerin injected through a respective annular gap of the nozzle disposedbetween the annular gaps through which the first and second materialsare injected, which material is selected to have a diffusion-inhibitingeffect on the substance to be contained in the tube body.
 10. The methodaccording to claim 9, the thermoplastic material which is injectedthrough the outer one of the annular gaps comprising polyethylene (PE),polyethylene glycol terephthalates or polyalkylene terephthalates (PET)or polypropylene (PP).
 11. The method according to claim 9, thethermoplastic material which is injected through the inner one of theannular gaps comprising polyethylene (PE), polyethylene glycolterephthalates or polyalkylene terephthalates (PET) or polypropylene(PP).
 12. The method according to claim 9, wherein the thermoplasticmaterial of the further layer comprises polyamide (PA) and/or (PE)and/or (PET) and/or (PP) and/or ethylenevinyl alcohol (EVOH) and/or PENand/or PVDC and/or polyethylene glycol terephthalates.
 13. The methodaccording to claim 6, wherein the tube preforms are cold-stretchable.14. A tube body preform, wherein the tube body preform is injectionmolded with a shoulder region that open towards the interior of the tubebody preform, and a closed end region.
 15. A tube body produced using amethod according to claim
 1. 16. A procedure for the production of atube body, comprising the steps of: a. injection molding a preform froma thermoplastic material; b. putting the preform into a blow mold; c.biaxially expanding the preform to form a container by stretching andsupplying pressurized blowing gas; d. removing the containers from theblow mold; e. cutting off a closed end region of the container to forman open end; f. pressing the opposite open end and a closure sectiontogether; and g. welding the open end.
 17. The procedure according toclaim 16, wherein the production of the containers is accomplished in atwo-stage procedure.
 18. The procedure according to claim 16, whereinthe production of the container is accomplished in a classifyingprocedure.
 19. The procedure according to the requirements of claim 16,wherein the procedure is accomplished using a stretch pin.
 20. Theprocedure according to the requirements of claim 16, wherein thecontainer is made of a preform with a single-layer structure.
 21. Theprocedure according to the requirements of claim 16, wherein thecontainer is made of a preform with a multilayer structure.
 22. Theprocedure according to the requirements of claim 16, wherein thecontainer is manufactured as a flask-shaped container.
 23. The procedureaccording to the requirements of claim 16, wherein the tube body ismanufactured as a tube.
 24. The procedure according to the requirementsof claim 16, wherein the tube body is manufactured as a bottle.
 25. Theprocedure according to the requirements of claim 16, wherein welding theopen end is accomplished before a filling of the tube container.
 26. Theprocedure according to the requirements of claim 16, wherein separatingthe closed end region and welding the open end is accomplished in aprocessing step.
 27. The procedure according to the requirements ofclaim 16, wherein the welding of the open end is accomplished afterfilling the tube container.
 28. The procedure according to therequirements of claim 16, wherein the open end is treated after welding.29. The procedure according to the requirements of claim 28,characterized in that the treatment is accomplished before the filling.30. The procedure according to the requirements of claim 28, wherein thetreatment is accomplished after the filling.
 31. A device for theproduction of a tube body, comprising an input mechanism for theadmission of a blow-formed container from a thermoplastic material;output mechanism for the removal of the tube body; and a cuttingmechanism located between the input mechanism and the output mechanism,the cutting mechanism being operative to cut off a closed end region ofthe container opposite a closure region of the container.
 32. The deviceaccording to claim 31, wherein the input mechanism is coupled to theoutlet of a blow mold that in turn in coupled to the outlet of aninjection mold.
 33. The device according to claim 31, wherein the outputmechanism is coupled to a drop mechanism.
 34. The device according toclaim 31, wherein the cutting mechanism is provided with our coupled towelding equipment.
 35. The device according to the requirements of claim31, characterized in that preparing the production of tubes is realized.36. The device according to the requirements of claim 31, for producingbottles.
 37. A tube body, which is designed as a separated part of ablow-formed and biaxial oriented container made of a thermoplasticmaterial, wherein a final section of the body, which is arrangedopposite a closure section, is joined by welding an open end of thecontainer formed by separating an end region of the container.
 38. Atube body, which is designed as a separated part of a blow-formed andbiaxial oriented container from a thermoplastic material, characterizedin that a final section of the body, is welded for a closure sectionopposite a floor part, which is relative to a side wall of the movableand sealed body.